Page 2 - Franzitta_et_alii_2017

Sustainability 2017, 9, 106 2 of 19
Sustainability 2017, 9, 106 2 of 19

adoption of clean and sustainable improvements. In fact, another field that European Government
of clean and sustainable improvements. In fact, another field that European Government studies with
studies with more attention is mobility. Numerous researches have demonstrated that the number of
more attention is mobility. Numerous researches have demonstrated that the number of vehicles in
vehicles in the world is expected to double in the next 30 years, which could have serious negative
the world is expected to double in the next 30 years, which could have serious negative consequences
consequences for energy security and the climate. The cause of this is the growing demand for cars in
for energy security and the climate. The cause of this is the growing demand for cars in countries
countries such as Brazil, China, India, South Korea, Mexico, Poland, Russia and Thailand as the people
such as Brazil, China, India, South Korea, Mexico, Poland, Russia and Thailand as the people there
there seek to increase their individual mobility when they become more prosperous [4].
seek to increase their individual mobility when they become more prosperous [4].
Figure 1 shows the correlation between the number of vehicles owned by people and the per
Figure 1 shows the correlation between the number of vehicles owned by people and the per
capita income.
capita income.

Figure 1. Correlation between the per capita income and the number of personal vehicles owned.
Figure 1. Correlation between the per capita income and the number of personal vehicles owned.
The most common effect of this above-mentioned amount is the increasing air pollution.
The most common effect of this above-mentioned amount is the increasing air pollution. Therefore,
Therefore, some new possible solutions should be investigated. Hydrogen is an energy carrier with
some new possible solutions should be investigated. Hydrogen is an energy carrier with great potential
great potential for clean, efficient power in stationary, portable and transport applications. It is
for clean, efficient power in stationary, portable and transport applications. It is envisaged as a
envisaged as a significant element of the future fuel mix for transport, enhancing energy security,
significant element of the future fuel mix for transport, enhancing energy security, reducing oil
reducing oil dependency, greenhouse gas emissions and air pollution. Hydrogen allows a wide
dependency, greenhouse gas emissions and air pollution. Hydrogen allows a wide diversification of
diversification of energy sources. In combination with fuel cells, it can also improve energy efficiency
energy sources. In combination with fuel cells, it can also improve energy efficiency in transport
in transport and contribute strongly to mitigating climate change—especially when produced by
and contribute strongly to mitigating climate change—especially when produced by renewable
renewable primary energy sources. Hydrogen and fuel cell technologies were identified amongst the
primary energy sources. Hydrogen and fuel cell technologies were identified amongst the new energy
new energy technologies needed to achieve a 60% to 80% reduction in greenhouse gases by 2050.
technologies needed to achieve a 60% to 80% reduction in greenhouse gases by 2050. Recent studies
Recent studies show the possible advantages of hydrogen’s introduction on bus fleet. Shaheen et al. [5]
show the possible advantages of hydrogen’s introduction on bus fleet. Shaheen et al. [5] showed that
showed that greater levels of exposure to hydrogen-fueled vehicles lead to higher levels of hydrogen
greater levels of exposure to hydrogen-fueled vehicles lead to higher levels of hydrogen acceptance and
acceptance and that early adopters tend to feel safer when using the technology, leading to significant
that early adopters tend to feel safer when using the technology, leading to significant improvements
improvements in public awareness. Langford et al. [6] presented Knoxville Area Transit (KAT) as a
in public awareness. Langford et al. [6] presented Knoxville Area Transit (KAT) as a case study to
case study to support the transition of a medium sized transit agency to full conversion to hydrogen
support the transition of a medium sized transit agency to full conversion to hydrogen fuel, describing
fuel, describing requirements for hydrogen bus fleets, production, storage, refueling and
requirements for hydrogen bus fleets, production, storage, refueling and maintenance facilities.
maintenance facilities. In the past decade, there have been several projects demonstrating the
In the past decade, there have been several projects demonstrating the feasibility of hydrogen bus
feasibility of hydrogen bus infrastructure, vehicles and operating procedures. Another interesting
infrastructure, vehicles and operating procedures. Another interesting benefit regarding hydrogen’s
benefit regarding hydrogen’s production, is that it can be obtained from a variety of sources, such as
production, is that it can be obtained from a variety of sources, such as fossil fuels or water, etc.
fossil fuels or water, etc. Technologies for the production of hydrogen from fossil fuels (steam
Technologies for the production of hydrogen from fossil fuels (steam reforming, partial oxidation,
reforming, partial oxidation, gasification) are, as mentioned, mature and widely used (more than 95%
gasification) are, as mentioned, mature and widely used (more than 95% of the hydrogen produced
of the hydrogen produced today comes from these processes). As for its production from renewable
today comes from these processes). As for its production from renewable sources, this comes from
sources, this comes from such sources as biomass or water. Currently, the European Parliament
passed a law on hydrogen vehicles’ homologation in an effort to protect the environment in urban centers.